cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A331379 Number of integer partitions of n whose sum of primes of parts is divisible by n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 4, 6, 7, 7, 7, 9, 11, 18, 24, 33, 39, 44, 51, 55, 66, 83, 106, 121, 145, 167, 193, 232, 253, 300, 342, 427, 469, 557, 628, 729, 846, 936, 1088, 1195, 1450, 1601, 1895, 2097, 2482, 2782, 3220, 3592, 4073, 4641, 5202, 5911, 6494, 7443, 8294
Offset: 1

Views

Author

Gus Wiseman, Jan 17 2020

Keywords

Examples

			The a(6) = 1 through a(11) = 7 partitions:
  111111  52       53        54         64          641
          1111111  62        63         541         5411
                   521       531        631         6311
                   11111111  621        5311        53111
                             5211       6211        62111
                             111111111  52111       521111
                                        1111111111  11111111111
For example, the partition (5,4,1,1) has sum of primes 11+7+2+2 = 22, which is divisible by 5+4+1+1 = 11, so (5,4,1,1) is counted under a(11).
		

Crossrefs

The Heinz numbers of these partitions are given by A331380.
Numbers divisible by the sum of their prime factors are A036844.
Partitions whose product is divisible by their sum are A057568.
Numbers divisible by the sum of their prime indices are A324851.
Product of prime indices is divisible by sum of prime indices: A326149.
Partitions whose Heinz number is divisible by their sum are A330950.
Partitions whose Heinz number is divisible by their sum of primes: A330953.
Partitions whose product divides their sum of primes are A331381.
Partitions whose product is equal to their sum of primes are A331383.
Product of prime indices equals sum of prime factors: A331384.

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n],Divisible[Plus@@Prime/@#,n]&]],{n,30}]